1. Field of the Invention
The present application relates to a circuit substrate structure, and more particularly to a composite circuit substrate structure.
2. Description of Related Art
In current semiconductor package technology, a circuit substrate is one of the most frequently used components. The circuit substrate is mainly formed by stacking a patterned circuit and a dielectric layer. The dielectric layer is commonly made of resin. Since structural strength of resin is relatively weak, a glass fiber structure can be distributed in the dielectric layer, so as to increase the structural strength of the dielectric layer.
In a circuit substrate having an embedded patterned circuit, when glass fiber is distributed in a dielectric layer, a patterned circuit is likely to contact the glass fiber structure in the dielectric layer. During an electroplating process, an electroplating solution possibly permeates into a gap between the glass fiber structure and the dielectric layer, and conductive metal is then formed in the gap after the electroplating process is performed. What is described above is called permeating. Two conductive wires in the patterned circuit may be connected through the conductive metal, thus giving rise to short circuit.
In addition, when a voltage is applied or moisture is increased in a reliability test, metal particles in the two conductive wires having a relatively small pitch therebetween move to the gap between the glass fiber structure and the dielectric layer due to electron mobility. Nonetheless, the metal particles accumulated in the gap cause short circuit in the two conductive wires having the relatively small pitch.